The present invention relates to a technology related to development, fabrication and test of LSIs in which an ID or a secret key has been installed.
In general CMOS LSIs, it is difficult to install different keys. Because, key is implemented in General CMOS LSIs by hard-wired logic or ROM. So, key is not able to changing. A key may be loaded from an external ROM. In this case, however, the key may be analyzed inside a system. Also, a person other than the key administrator, such as a network distributor, an LSI designer and a set designer, may possibly come to know the key. In addition, it is difficult to write keys with different values by mass-production technology. The package may be unsealed for chip analysis. Moreover, there is no way to verify whether or not the key has been installed correctly. That is, testing of internal keys is difficult.